Mercury switch



BEST AVAILABLE COP\ Nov. 16 1926.,

R. D. MAILEY MEHCURY SWITCH Filed May INVENTOR TTORNEY Patented Nov. 16, 1926.

UNITED STATES BEST AVAILABLE COP\ P ATENT OFFICE..

BOY D. MAILEY, OF EAST OBANGE, NEW J ERSEY, ASSIGNGR TO COOPER-HEXVTT ELEG- TRIC COMPANY, OF HOBOKEN, NEW JERSEY, A CORPOBATION 0?? NEW JERSEY.

MERCURY SWITCH.

Application filed May 26 My present invention relates to switches for electric circuits in which movementsvof the liquid mercnry in said switches achieve the making and breaking of the electrc condncting path therethrough. It particularly relates to such a switch in which provision is made for the automatic opening thereof at normal or at excessive temperatnres when the switch is usedwith heating apparatus or apparatus which becomes 'or may become heated during use and availing of the temperature of the heating device to cause the transfer of the liqnid mereury from between the' terminals of .the switch to open the circuit therethroughfl:

Electric heating apparatusespecially of the domestic tvnes are a recognized source or" fire hazard and this is'especiallyv true in the case of electrically:heated fla i'ois although my invention is applicab'le to heating or' heated apparatus 'in thearts generally. Many devices 'are known whose'obj'ect itis to eliminate or `circumvent this hazard but heretofore results:: therewith have not been entirely satisfactory It is'the object' of my .inventionto *provide a s switch for electrical ?heating ?apperatus which will automatically 'open the:cir--, cuit therethrough' when: such'devices 'are'left 1924. Serial No. 715380.

between the eiectrodes and -the body.

Fig. 3 is an elevation of a U-tube switch having nercury thercin, eiectrodes in the legs oi' the U one or both ot' which has a sheathing of insulating material thei-een, and a condensing chamher for each ot' the legs near its top.

Fig. 4 is a side elevation View of the switch of Fignre 3 without the insulating coating or sheathing.

` F ig. 5 is a plan View OI" the switch of Figure 3.

The devicebf my'invention comprses a body of mercnry, or of some other-snitabie substance,s which is enclosed in the chanber of a vitreous envelope of such material as glass. Thronghthe walls' of the envelopc and i`n= contact with the. said .body of mer-` cu'y, fone'xample, are3sealed electrical con- -dnctors which on their outer encls' are suitably connected to electric mains and hezitng apparatus. Connectingwith the said chamber near-.itstop is a condensing chamber -'forc' thei condensation and collection therein. of vaporized mercury or the like passing; thereto from the main chamber. Mans ;isrprovided for preventing the -fiow jofthe contlensd mercury.- back into ti e standingwith"the"currenttirned'onthfoigh t min" chamberx-Suchj means as described the switch.

-It is another object of'my inventiorr to provide ,such a thermostatic switch which is simple'of operation, fool` proof, and simple of Construction. i

It is another object of my inventionto provide' such a switch. which will 'itoinatically: open when' the `devce iri-:which it is used is out of its normal'position.

` It is another 'obj ect of my invention to provide 'an' electric flat ironfswitch' which .will continue to function to open at normal or excessi've, temperatures; which is automatically closed'by the' motion of the iron inits-nse,

but will function to open and remaineopen if left standing in the'operative position.-

'Fig. 1 is &vertical sectional' view` of--an electrically heeted flat i iron to" 'which the switch'of' my'invention is appled. i'

Fi'g; 2 is an elevation View of a switch embodying my invention in which the'electrode leads are sheathed in surrounding tubes extending below 'the'lower extremities of the electrodes and providing: spaces at the ter-- minals for the makingjand breaking of arcs below; and shown in the .drawingsmre eni- `-bodedf in a lower floor or boundary for such condensingchamben which recedes from the mainchambr' to -form with' the 'other walls of said chamber a i liquid collecting ocket. Another Jen'bo'diment shown and ,described is a raised rim oriidge at theconfluence of ,the-two chambers which-rim or -ri'dge serves as a damto hold *back and-;collectcondensed liqnid in the condensing chanber( Snch recession of-th'e floor or such raising of a rim is of such degree as' to permit, o'r instance in the use' of my switch in an electric heated flat iron, of a' constant; and continuons re- 'turn of the mercury .or other hquid coliected in the. condensing chamber through the normal movement of the iron in its use i'c;- ironing. Vhen the iron is in use and the switch'in almost constant mot-ion the condens'ed m'ercury is continually returned to the main body and the switch left closed.

Any cessation of motion will pernit the' ac- `cumniation ot' mercury in the condensing chamber and a continued inactvty will res'ult'n the opening of the switch, and` the llO by distillation and condenses. This subchamber is so constructed with respect to the main envelope or chamber that the mercury which distills thereto and condenses therein can be easily and quickly moved back to the main chamber by a simple movement of the switch or of the apparatus in which the switch is installed or by its normal movement in the use of the apparatus in which it is installed.

As an example I shall describe the use of the switch of my invention in connection with an electrically heated flat iron.

In the drawings is shown an envelopel as of glass having a condensing subchamber near ts topoand the level of the bottom boundary of which lowers away from the main chamber. Through the walls of the envelope 1 are sealed electrodes 3 and 4 which in the normal position and condition of the switch are connected by the body of mercury, 2 within said envelope. Undernormal Operating; or excessive' temperature, a part of the body of= mercu:y--2 will be distilled therefrompassing into chamber or ocket 18 where it will condense.: and accumu ate. This distillation and. ac-

cumulation will continue while such normal'- or excessive temperature is maintained whenthe switch is at rest untilsuicient mercury passes from the main body 2-todisrupt the electrical conducting path* between electrodes 3 and 4.

In Figura 1 is shown flat iron 10 into the body of which is inserted the lower part of the switch envelope 1 the said' lowerpart= Situated near the heatingelement :11 of the iron and showing the subchamber orpocket 18 as Situated outside and away from said heating element. Said lower boundary of the subchamber or pocket 18 is substantially a plane terminating in a rim 14: at the juncture thereof with the main body 1 of the switch so that whenthe switch is suiciently tilted in the direction away from said pocket any mercury therein will flow back into the main chamber 1. In this position the main body of mercury 2 is subjected to the temperature of the iron while the subchamber or pocket 18 remains always at a much lower temperature when the iron the sub-.

BEST AVAILABLE cop\ is heated'and at a temperature at which any mercury distilled thereto from body 2 will condense and accunulate therein.

In the operation of the first form of the device of my invention, using the clect'ical heated flat' iron application as an example when the flat iron is in its normal positon and current turned the'eon a conducti' path. will; continue therethrough until temperature is reached such that. will the distillation of mercury vapor from i mercury body 2 and the passing thei-cof pocket 18 and the condensation thereof said pocket where it will accumulate in ;e

body. This distillation, accumulatim, :zani 1242 condensation ,will continue while such temperature prevails until the con lncting pati; between electrodes 3 and 4 is disrupted and the current through said heating element 1.2.

is discontinued whereupon the temperature in said iron lowers and any danger of i-:a: hazard. throughit is averted. To return tiumercury accumulated in chamber 18 to the main body of mercury 2 the iron is s mply Shaken or tilted to cause said mere-my to flow back to the body 2.

In Figure 2 is shown a form of'my invention in which the electrodes 3 and l are sealed through the top of the envelopc l of the switch, each of said electrodes being surrounded by the glass tubes 12 which extend beyond the inner ends of the electrodes to provide restricted spaces about said ends and which serve to a degree to quench oi' dissipateany arcing that takes plac on th movement-of the me'rcury away from such ends. About mid'way between theends of 'suchtubes 12:,are. the-holes 13' which serve to equa-IiZe-vapor pressures throughoutsaid tubes 12 and the interior of envelope 1. The rim 14 between chamber and condensin cha'mber; 5-is of'such height as to hold suflicient mercury on the substantially horizontal' floor 15 of chamber 5 to result in the opening of the circuit between elcctrodes and 4:.

In Figures 3, 4 and 5 is shown the switch body- 1 which is substantially a sealed U- tube to.the upper part of the legs 17, 17 of which connect into the condensing chamher- 5, 18,' 18 respectively. The electrodes 3 and 4: are sealed in throughthe tops of the leis 17 17 and extend into the mercury body In this form of my invention upon the. evaporation of mercury` from body 2 and its condensation andany arcing which might -occur between the electrodes and the mercuryin cases where the current therethrough is heavy enough to sustain an arc the carrying on of the arc to the electrodes themselves is prevented by the length of the path presented between the electrodes.

hen desired, the switches may be filled with suitable gas such as hydrogen, nitrogen, etc. for dissipating the heat at the instant of breaking of the circut and to serve also in quenching any are which would tend to form. I

This application is a continuation in part of my application filed October 27, 1923, Serial Number 671,104:.

I claim 2- 1. In a mercury switch in combnation, a sealed envelope comprising a main chamber and a condensing chamber, a body of mercury in said main chamber, electrodes sealed through the walls of said envelope and eX- tending into said body of meren y, and insulating sheathings of Vtreous material on said electrodes extendng to within a short distance of the inner ends of said eleetrodes, the lower floor of sai-d condensing chamber being substantially horizontal, and a low rim or ridge extending across said lower floor at the confluence of said main chamber and said condensing chamber.

2. In a mercury switch, in combination, a sealed envelope comprisng a main chamber and a condensng chamber connecting therewith, said condensng chamber having a substantially horizontal lower floor and a ridge extendng across said floor at the con- BEST AVAILABLE cop# 8 fiuence of said chambers, a body ot' mercury in said main chamber, electrodes extending from the top of said chamber and into said body of mercury, and Vitreous insulating sheathings on said electrodes extending to within a short distance of the inner ends of .said electrodes.

3. A mercury switch comprising a sealed U-tube envelope having condensing' ehambers conneoting at substantiaily right angles with the upper ends of the legs o' said U-tube, a ridge or rini extending across the lower fioors of said condensing chamber at or near their confiuence with said U-tube legs, a body of mercury in said enveiope electrodes sealed through the walls of said envelope at the tops of said U-tube l-egs and eXtending into the body of mercury in said envelope,

and coatngs of Vitreous nsulating material eovering said electrodes used to said envelope at the seal-in end extending to within a short distance of the inner ends of said electrodes.

Signed at Hoboken in the County of Hudson and State of New Jersey this 22nd day of May A. D. 1924.

BOY D. MAILEY. 

